今ちょっとIndiana Bureau of Motor Vehicles (BMV) の FAQ のセクション読んでみたら、こう書いてあります:
Q: "Can I drive in Indiana with an out-of-country driver license?"
A: "An individual who does not intend to become a resident of Indiana may drive in Indiana on an out-of-country license for a period of one year. The individual also must carry an international driving permit with the out-of-country driver license while driving in Indiana."